Telephone-exchange system and apparatus



(No Model.)

H. H. ELDRED.

TELEPHONE EXCHANGE SYSTEM AND APPARATUS.

No. 303,714. Patented Aug. 19, 1884.

g ilnrrnn STATES PATENT @FFICE,

HORACE H. ELDRED, OF NEXV YORK, N. Y., ASSIGNOR, BY MESNE ASSIGN MENTS,TO THE \VESTERN ELECTRIC COMPANY, CF CHICAGO, ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM AND APPARATUS.

SPECIFICATION forming part of Letters Patent No. 303,714, dated August19, 1884.

Application filed Ju To all whom it may concern.-

Be it known that I, I'IORACE H. ELDRED, a citizen of the United States,and a resident of the city, county, and State of New York, have inventedcertain new and useful Improvements in Telephone-Exchange Systems andApparatus, of which the following is a specification. Y

My invention relates to a method of intercommunication known as thedistrict exchange telephone system, and it consists, in general, ot'acentral or exchange station, which is connected with a numberot'sub-stationsby means of telegraphic or telephonic lines radiatingtherefrom, these latter being so organized and arranged that any two ofthe substations may be placed at amoments notice in direct telegraphicor telephonic commnnication witheach other by the act of an attend antat the central or exchange station, who, upon being notified to .do so,connects together the two lines leading to the respective substations,so that they are enabled thereafter to com municatc with each otherdirectly.

My invention consists in the combination,

with a series of telephfonelines converging to a central station from acorresponding number of sub-stations, hereinafter termed substationlines, of a switch -board consisting of a series of spring-jacks-one foreach linefor the insertion of wedges or other equivalent devices foreffecting changes in the connections of the several lines, and a seriesof visual signals or annunciators-one for each line-for indicating theparticular line or spring-jack with which a connection is required tobemade, one of these visual signals placed on each line at a point betweenthe said springjack and the earth, to which all the lines are normallyconnected, whereby, when any two independent lines are temporarilydisconnected from the earth and coupled 'together to form a combinedcircuit, their corresponding annnnciators are excluded there- 5 from.

The invention further consists in the combi nation, with thehereinbef'ore-described system of lines converging to a central station,of movable switches and conducting bars or strips united in pairs,withbranch or loop conductors at said stat-ion, whereby direct communicationcan be established between any two substations by connecting theirrespective lines together at the central station, and

a signalingapparatus included in each of said 5 5 branches, loops, orconnecting-conductors, whereby, after having been thus connectedtogether, the two substations or either of them may notify the attendantatthe central station to disconnect the said lines.

The invention further consists in the com- -bination, with the apparatuslast mentioned,

of a signal sending and receiving apparatus and a telephone mounted uponan auxiliary or operators table included in aloop-wire,

which wire is provided with a wedge for insertion into a spring-jackplaced in any one of the branch, loop, or connecting conductors,together with a switch, whereby said loop may be divided and the legthereof containing the signaling apparatus and telephone connected withthe earth.

v The invention further consists in various details of construction andorganization of the apparatus, whereby its efliciency and con; 7

venicnce of manipulation are enhanced, which will beherei nafter moreparticularlydescribed and claimed.

In the accompanying drawings, Figure lis a theoretical, plan showing thegeneral arrangement of the switch-board and other apparatus at a centralstation, and embodying my improvements; and Fig. 2 is a sectional viewof the spring-jack and wedge which is employed for etiecting theconnections at the 8 5 main switch.

In Fig. 1 I have shown, for the purpose of illustrating my invention, acentral exchange or station having six independent lines, which connectwith different substations.

The apparatus at each of the several substations is arranged in awell-known manner, and consists of an instrument for transmitting andreceiving calls, alarms, or signals, to

gether with a transmitting and receiving telephone, which may beseparate or may be combined in one instrument, as most convenient. Itmay be remarked that any convenient number of lines connecting with asmany difi'erent' sub-stations may be grouped together in this manner,according to the requirements of the service. The signaling andtelephonic appa ratus at each substationis assumed to be con-. nected inthe usual manner with the earth, and also by means of its appropriateline-wire with the central station shown in the figures. These severalsub-station line-wires are numbered in Fig. 1 of the drawings as 1, 2,3, 4, 5, and 6. Upon entering the central station each line is extendeddirectly to the switchboard S, which consists of a row of springjaeks, JJ J", 850., which are constructed so as to press firmly againstcorresponding me tallic plates, 0 e", &c., and thus form an electricalconnection therewith. Each spring-jack is connected with or attached toone of the separate lines leading to the several sub-stations, and theseveral springjacks may be 0011- veniently designated by a numbercorresponding to the one which serves to distinguish that line, asillustrated in the drawings.

I will now proceed to describe the instru mentalities which I prefer toemploy for coupling the different wires together at the central stationin pairs for direct communication between independent sub-stations. Aflexible insulated conductor, M, usually termed a switelrcord, isprovided with a terminal or wedge, N, at one of its extremities. Thedetails of the construction of this wedge and the manner in which it isapplied to the switch may be best seen in Fig. 2, which represents asectional view of one of the spring-jacks of the switch with the wedgeinserted therein, in order to make a connection between one of the linesand the central conductor.

In Fig. 2, D is a slab of wood or other nonconducting material, to whichthe parts of the apparatus are secured. The spring-jack J is formed atits upper extremity into a metallic block, which is mounted upon theslab D and secured thereto, and by means of a suitable binding screw iselectrically connected with the wire 1, which is united to one of thelines extending to a substation. The contact-plate upon which eachspring-jack rests is connected with its own independent annunciator,indicator, or visual' signal W WV WV by a wire, which, after passingthrough said annuneiator, is joined to the earth-wire 20, which iscommon to all the lines when normally connected. By this arrangement itwill be observed that the annuneiators, indicators, or visual signalsare placed between the switchboard or spring-jack and the earth, insteadof being between the switch and the line, as has heretofore been thepractice. An important advantage gained by this arrangement consists inthe fact that when two lines are coupled to gether at the centralstation for direct communication the annunciators belonging to theselines are thrown out of the combined circuit, and thus the resistance tobe encountered in passing through the central station is greatthe room.

nected with one terminal of the spring-jackj" 1y diminished. The spring-jacks may be normallykept firmly in contact with the plates on whichthey rest either by their own re silieney or by means of springs. Theterminal or wedge N has one of its faces,a,formed of metahand the otherface,n, of non-conducting material,the former face being electricallyconnected with the flexible insulated conductor M. When, therefore, thewedge is inserted beneath the spring-jack, as shown in Fig. 2, thepreviously-existing connectionbetween the li ne-wire 1 and the earth-wire 20 is interrupted, and the former is placed in connection through themetallic face n of the wedge with the conductor M; butif the wedge bewithdrawn the line is automatically and instantly restored to its normalconnection with the earth. The opposite extremity of the flexible cord Mterminates in a tapering metallic peg, P, which may be inserted with atwisting motion into one of anumber of suitable holes provided for thatpurpose in the horizontal metallic bars or strips a a, b 1/, 00, whichare insulated from each other by the non-conducting base-board, andplaced preferably above the spring-jacks upon the switch-board S,asshown in the drawings. These bars are coupled together in pairs, eachpair, as a a, being connected by wires 7 8, forming a branch or loop,and having inserted therein one of a series of auxiliary springjacks, jjj and which are mounted upon the operators table A in any convenientpart of For example, the bar a is conby a wire, 7, which also passesthrough a visual signal or annunciator, R,which is operated by anelectro-magnet in a well-known manner,so as to display an indicatingdevice when- 6W3! the magnet is traversed by the current. The otherterminal of the spring-jack is connected directly with the bar a byanother wire. m

Upon or beside the operators table A is placed an apparatus fortransmitting and re ceiving calls, signals, or alarms. I prefer toemploy for this purpose a magneto-generator operated by a crank, 70, andwhich transmits a series of successive electrical pulsations alternatelyof opposite polarity. The bell r, for receiving calls, alarms, orsignals, is operated by an clectro-magnet. A telephonic transmitter, T,and a telephonic receiver, t, with the usual switch, which may beautomatic or non-automatic,for throwing either the signaling or thespeaking apparatus into the circuit at pleasure, is also provided. Thisapparatus is placed in a looped wire or circuit, one leg ofwhich,h,terminates in one side of a doublefaced wedge, U,while the otherleg, h, goes to the lever of a circuit-changer, S, on the operatorstable A. When this circuit-changer is moved to the right, it completesthe loop through the wire h to the opposite face of the wedge U, butwhen turned to the left, as in the figure, it connnects the leg h of theloop directly to the earth at G.

ICS

The operation of my improved system is as follows: When a call signal istransmitted from one of the sub-stations (say upon the line numbered 1)to the central office, the corresponding annunciator-drop or othervisual signal, W V W WV N W, connected with the wire is actuated,notifying the attendant at the switch, who immediately takes one of theflexible conductors M and inserts its wedge N into the spring-jackbelonging to that line which is directly beneath the indicator, and thepeg l? at its other end into the lower bar, a, of the unoccupied pair ofbars, a a. The operator at the table A at the same time inserts thewedge U into the corresponding spring-jack, j, the circuit changer Sbeing normally turned to the left, as shown in the drawings. The effectof this is to connect line-wire No. 1 with the earth at the centralstation by the way of flexible conductor M, bar a, branch-wire 8, wiresh and h, and cir cuit-changer S, including the telephonic and signalingapparatus upon the operators table. The operator then immediatelyascertains, by speaking through his telephone, what line the sub-stationcalling desires to be placed in connection with, and calls out to theswitchman (for example) that No. 6 is wanted,whereupon the switchmaninstantly connects No. 6 with the upper bar or strip, a, by means ofanother cord, M, with its wedge N and peg 1?, as in the former case,while the table'operator at the same moment turns the circuit-changer Sto the right. The two lines, No. 1 and No. 6, are now entirelydisconnected from the earth at the central station, and are uniteddirectly with each other through the telephonic and signalinginstruments in the loop-wire h h. The table-operator now signals thesub-station on No. 6 by means of alternate positive and negativecurrents transmitted over the line from his magneto-generator, and uponreceiving a response to his signals informs him who is connected withhim, and this, being heard also on No. 1, informs that substation thatthe desired connection with his correspondent has been made. draws thewedge U, leaving the two substations in connection with eachotherwithout any instrument in the circuit at the central office exceptthe auxiliary annunciator or vis ual signal R in the branch or loopcircuit which connects the two lines. As soon as the two sub-stationsthus connected have finished their conversation, one or the other ofthem, by operating the signaling apparatus, produces an indication uponthe annunciator R at the central station in the usual manner, whereuponthe table operator notifies the switchman to disconnect Nos. 1 and 6 andre store them to their normal position, and this having been done, theentire operation of connection and disconnection is completed.

By the use of my improved system connections and disconnections may beeffected in a telephone exchange system with great facility Thetable-operator now withand convenience, evenwhen the number of lines isvery great, inasmuch as I am enabled to divide the work between one ormore tableoperators and a switchman without introducing any elements ofcomplication or confusion.

I claim as my invention- 1. The combination, substantially ashereinbefore set forth, of a series of telephonelines converging to acentral or exchange station from different sub-stations, a series ofspring- 'acksoue for each linefor the insertion of connecting wedges,and a series of visual signals or calling-annuuciators, \V WV N W XV",one of which is placed in each line at a point between its spring-jackand the earth, whereby the annuuciators are cut out while talking.

2. The combination, substantially as hereinbefore set forth, of a seriesof telephonelines converging to a central or exchange sta tion fromdifferent sub stations, movable switches and conductors 7 8, &c., atsaid central station, whereby direct communication can be establishedbetween any two sub-stations by connecting both their respectivelinestogether, and an auxiliary or supplemental signaling apparatus, R, &c.,ineludedin each of said connecting-conductors, whereby the sub-stationsso connected, or either of them, may notify the attendant at the centralstation to disconnect the said lines.

3. The combination, substantially as here inbefore set forth, of aseries of telephonelines converging to a central or exchange stationfrom different sub stations, movable switches and conductors at saidcentral station, whereby direct communication can be established betweenany two substations by connecting their respective lines together, aspring-jack in each of said connectingconductors, an apparatus I fortransmitting and receiving calls or signals, and telephonic apparatusincluded in a loop which is provided with awedge for insert-ion intosaid spring jack, and a circuit-changer whereby said loop may be dividedand the leg containing the signaling apparatus and telephone connecteddirectly with the earth.

4. The combination, substantially as here inbefore set forth, of aswitch-board, an auxiliary table, telephonic or electric apparatuslocated upon said table, and devices for establishing temporaryelectrical connection between one or more lines centering in i said tble, communication between sub-stations and the central station orbetween different substations being established -through the tableapparatus.

5. The combination, substantially as here inbefore set forth, of aseries of visual indicators at a central station, a series ofindependent substation lines converging tosaid central station, eachpassing through its respective indicator, and thence to a normalconnection with an earth common to all of said lines, an operatorstable, and devices for temporarily disconnecting one or more of saidlines from. the earth and simultaneously connecting them with saidtable.

6. The combination, substantially as here inbefore set forth, of aseries of sub-station lines converging to a central station, a series ofconducting bars or strips permanently connected with an operators table,and devices for temporarily connecting one or more of said lines withsaid bars or strips.

7. The combination, substantially as hereinbefore set forth, of a seriesof substation lines converging to a central station, a series ofspri1igjacksone for each linea series of conducting bars or strips, andflexible conductors armed with suitable plugs or terminals fortemporarily establishing electric connection between one or more of saidlines and said bars or strips.

8. The combination, substantially as hereinbefore set forth, of a seriesof sub-station lines converging to a central station, a series ofannunciators or indicatorsone for each linea series of springjacksonefor each linea series of conducting bars or strips, and

flexible conductors armed\vith suitable plugs or terminals fortemporarilyestablishing electric connection between one or more of saidlines and said bars or strips.

9. The. combination, substantially as hereinbefore set forth, of aseries of substation lines converging to acentral station, a series ofconducting bars or strips, a series of branch or loop circuits, eachuniting a single pair of said bars or strips, and means for forming atemporary electrical connection between any two lines and a pair of barsor strips.

10.. The combination, substantiallyas hereinbefore set forth, of aseries of conducting bars or strips, a series of branch or loopcircuits, each uniting a single pair of said bars 0: strips, a series ofspring-jacksone in each branch or loop circuit-a telephonic apparatus,

and a flexible conductor armed with a suitable terminal plug forconnecting said apparatus with any of said branch or loop cir cuits.

11. The combination, substantially as here inbefore set forth, of anumber of springjacks, a plug for insertion into said springjacks, aswitch, central-office instruments, and connections from saidinstruments to the points of said switch.

12. The combination, substantially as hereinbefore set forth, of aseries of sub-station lines converging to a central station, anoperators table, devices for temporarily connect ing one or more of saidlines with said table, an electric generator, and key and switchmechanism upon said table for connecting said generator and key with anyof the lines connected with said table.

13. The combination, substantially as hereinbefore set forth, of aseries of indicators with a series of corresponding sprii'ig-jaclzs,each indicator being placed in proximity to its respective springjack.

14. The combination, substantially as hereinbefore set forth, of one ormore operators tables, one or more indicators, and controlling mechanismtherefor located upon said tables.

15. The combination, substantially as hereinbefore set forth, of aseries of independent lines or conductors, one or more branch or loopcircuits, one or more central-office instruments, means for unitinganytwo of said lines or conductors with each other through one of saidbranch or loop circuits, and means for switching one or morecentral-office instru ments into or out of such branch or loop circuit.

16. The combination, substantially as hereinbefore set forth, of avseries of main lines converging to a switch at a central station,tlevices for uniting any two of said lines for oral communication,apparatus included in each line at the central station to indicate acall or signal, and independent devices for connect ing either line to apolechanging apparatus for transmitting outgoing signals.

Signed by me this 28th day of April, A. D. 1880.

HORACE ll. ELDRED.

\Vi tnesses:

\ VM. TROLLER, J12, II. L. Siro'nitn.

